<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
  <form action="/up" method="post" enctype="multipart/form-data">
    <input type="file" name="file">
      <button type="submit" value="提交"></button>
  </form>

</body>
</html>